1. Field
Embodiments provided herein generally relate to automated self-compensation apparatus and methods for providing electrochemical sensors, and particularly to making measurements of gases with electrochemical sensors of the type marketed worldwide for electrochemically active gases.
2. Technical Background
There is currently a need for making measurements of gases with amperometric (electrochemical) sensors for electrochemically active (ox-redox) gases. The current sensors may respond to a target gas, such as carbon monoxide (CO), oxygen, hydrogen sulfide (H2S), etc. and also to changes of an environmental factor, such as changes in temperature (T), pressure (P), and relative humidity (RH) that fluctuate depending on the day, weather, and user situation. In many current solutions, the temperature coefficient is measured in an environmental chamber by calibrating a CO sensor at different temperatures and then measuring the effect of temperature on the signal.
While these solutions may provide some improvement to previous designs, the signal and background also vary with relative humidity and such variation can be realized as a slow change measured over hours, days, weeks, or months. Currently there is no way to correct for such drift. Many current sensor manufacturers go to great lengths to design sensors to minimize this effect by using extremely large electrolyte reservoirs and very small gas access ports. Again, while these solutions may have some benefits, these designs result in bulky sensors, added expense, low sensitivity, poor performance, and inevitable failure.